I’m not sure if anyone’s posted this link yet, but Navionics shows off their Sonar Chart feature here a bit for almost all of the US.
Go to http://www.navionics.com/en/webapp – then toggle back and forth between the sonar pattern button you see on the lower left for the lakes you fish.
For the coastal Chesapeake Bay areas I’m currently scouting, there’s a big difference between the two datasets. For many of the lakes in MN, perhaps not so much.
Either way, it’s a great scouting/planning tool, check it out.
Joel